Body area networks (BANs) are known (refer to, for example, IEEE802.15.6). The BANs are very short distance radio communication networks for medical care and health care.
For a BAN, a sensor (hereinafter referred to as “node”) is downsized. In addition, for the BAN, a gateway device (hereinafter referred to as “hub”) is downsized and a battery is used for driving. It is, therefore, preferable to save power for the overall network. If data that is detected by the node indicates urgency, the data is reliably transmitted with a short delay time.
A technique for allocating a slot for urgent data to a superframe and providing slot allocation information for the urgent data to a node is known (refer to, for example, Japanese Laid-open Patent Publication No. 2011-87295).